Improved method op purifying- nitric acid



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Letters Patent iVm-94,969', dated September 21, 1869.

I IMPROVED METHOD OF PURIFYING- NITRIC ACID.

The Schedule referred to in these Letters` Patentvand making part of thesame.

To all whom it may concern `is performed by heating the distilledproduct of the rst distillation in glass balloons, and boiling the sameuntil it becomes colorless, and the chlorine and nitrous-acid gases areremoved. This mode, as Very concentrated nitric-acid, specific gravity1.500, passes into vapor at 184 Fahrenheit, or thereabouts, involves aloss pf concentrated nitric acid, and the result is a nitric acid ofspecific gravity 1.420, whose boilingpoint is 320io Fahrenheit, and aloss of the mostfconcentrated acid.I My process consistsin passing astream of warm atmosperic air through the nitric acid in the receiver,which, in a few minutes, becomes colorless in consequence. A portion ofthe nitrous-acid gas is thereby converted into nitric acid, and aportion passes off into the atmosphere with thecurrent of air.

If the condensed nitric acid to be operated upon is warm, as immediatelyafter the distillation from sulphuric acid and nitrate soda or nitratepotash it neces sarily is, then cold atmospheric air passed through thesame is equally efficient. If, however, sufficient time has elapsed toAcool the distillate, Vthen a current of warm air is more eliectual.

A A represent lpart of a battery of condensers, of the usual form usedin chemical factories.

B B are the connecting-pieces.

G is auiron pipe leading from either an air-pump or compresser, wl;encea supply of air suiciently compressed to overcome the height of thecolumn of air in the receiver.

D is a stop-cock, to command the supply of air.

E is a flexible rubber tube, connecting with F, a glass tube passing tothe bottom of the acid t'o be purified.

The operation is as follows: v

' Having secured a supply of compressed air, the stopcock D is opened,the air passes through the exible tube E, vpresses the column of air outof the glass tube F, andv issues through the acid or mixture o acids inthe receiver, and passes out of the receiver. As soon as the red fumescease to appear, the stopeock is closed, and the glass tube is insertedinte `the next receiver, and so on to the last, until the acid iscolorless.

By this method the acid is rendered colorless without incurring the lossof a considerable quantity or percentage of the most concentrated nitricacid, as is the case when the distillate is transferred to a glassballoon and heated in a sand-bath, according to the,

mode usually practised in chemical factories.

Having thus described the nature of my invention, its principles, andmodeof operation,

That I claim as my invention, and desire to secure by Letters Patent, is

The process of separating nitrous-acidgas from nitric acid or otheracids that may be mixed therewith,

substantially as described. GEO. M. M-OWBRAY.'

Vitnesses:

J. J. HOLDEN, HARRY Mo WBRAY.

